Environmentally friendly building materials and interior/exterior finishing materials are receiving attention these days because of the environmental problems they cause. Such finishing materials include interior sheets/films, including decoration sheets (hereinafter, referred to as “deco sheets”), wallpaper, flooring materials, or adhesive films which are to be attached for advertising and external appearance purposes. In particular, deco sheets are sheets suitable for being used to represent a decorative pattern such as a wood pattern on furniture, such as wardrobes, sink tables, storage closets, etc., and are typically utilized to express a wood pattern or other patterns on a wood plate resulting from renaissance trees because raw lumber is very expensive.
Unless otherwise stated, the meaning of the term “interior sheet/film” used in the present invention may include all of deco sheets, wallpaper, flooring materials, or adhesive films.
Such interior sheets/films have been produced to date from a PVC material using a calendering process which is able to produce a sheet which is thin and wide. However, the material used contains environmental hormones and may generate dioxin upon combustion, and is undesirably harmful to the health, responsible for sick house syndrome, for example. Hence, there is an increasing need for environmentally friendly materials.
Examples of such environmentally friendly materials include polyolefn resins such as polypropylene, polyethylene or mixtures thereof. However, polyolefin resins which are non-polar have poor printability and adhesiveness compared to those of conventional PVC and are difficult to print on or adhere using a conventional machine for applying PVC ink or adhesive. Furthermore, although corona treatment may be performed to impart printability, this may increase the number of processing steps and make it impossible to perform printing after the passage of a predetermined period of time.
In order to increase printability, expensive non-polar ink is used, undesirably increasing the cost of products, and furthermore this may remarkably deteriorate printability compared to conventional PVC in interior sheets/films which require precise printing. Also in order to enhance adhesive force, primer pretreatment may be conducted before an adhesive is applied, undesirably increasing the number of processing steps and raising the cost of products.
Patent literature 1 and patent literature 2 disclose a polyolefin resin including polyethylene terephthalate (PET), etc. However, these patents do not pertain to interior sheets/films, and are useful in producing vessels such as bottles, trays, etc. and secondary processing products on which it is easy to perform vacuum molding.
Accordingly, the demand for a commercially available polyolefin resin having superior printability and adhesiveness is increasing.    Patent literature 1: Japanese Unexamined Patent Application Publication No. 2006-137910    Patent literature 2: Japanese Patent No. 3856948